Quadrature downconversion to a very low IF frequency is a promising idea but it has one serious problem.Unavoidable imbalances in the analog front-end between the Iand Q-branches result in finite and usually insufficient rejection of the image frequency band which causes interference. We carry out the signal analysis of an imbalanced low-IF receiver and propose a novel baseband correction structure utilizing an adaptive interference canceller. Theoretical and simulation results are provided in order to evaluate the performance of the proposed idea. The results indicate that the V Q imbalance can be effectively compensated during the normal operation of the receiver, even in the rapidly changing case, as long as a linear system model for the imbalance is valid.
Throngh the introduction of mnltiple antennas in fut� wireless communications systems, the requirements for the power consumption, cost and size of indkidnal radia front ends become even more challenging than in the current single antenna systems. In tm'> cODten, the so called direct-conversion front-end architectm'e is of big interest for building compact ra
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